The verb 'squirm' is a relatively recent addition to English, first appearing in the late 17th century. Its origins are not definitively traced to a classical language but are considered imitative or expressive, likely a blend of the sense and sound of words like 'wriggle' and 'worm', evoking the image of a worm's sinuous movement. The addition of the '-ing' suffix, from the Old English present participle ending, transforms it into an adjective describing the state of performing that action or a noun naming the action itself. Thus, 'squirming' literally means "the act or state of making worm-like, twisting motions," a meaning that has remained consistent from its physical origins to its modern application describing both physical and psychological discomfort.

Structure: squirm + ing - squirm: Likely of imitative origin, possibly influenced by 'worm' and 'wriggle'. It functions as the verb root meaning to twist or wriggle. - ing: From Old English '-ende', '-inge', a suffix used to form the present participle (adjective) or verbal noun.